Development of a Micropropagation Protocol for the Ex Situ Conservation of Nuttall's Scrub Oak (Quercus dumosa).

Worldwide, oak species are threatened with extinction due to habitat loss, pathogens, and changing fire regimes. Ex situ conservation through tissue culture may protect the remaining genetic diversity of Quercus dumosa, or the coastal sage scrub oak, from further loss. We designed three basal salt formulations based on the mineral composition of shoot tips and first leaves from mature Q. dumosa and explored carbohydrate source, stress-mitigating compounds, and plant growth regulator concentrations to develop a method of cultivating many Q. dumosa culture lines in vitro. All three novel basal salt formulations led to decreased necrosis compared with commercial basal salt formulas WPM, MS, and DKW. Substitution of 30 g L-1 sucrose with glucose and adding 250 mg L-1 ascorbic acid, 5.2 mg L-1 SNP sodium nitroprusside, and 103 mg L-1 y-aminobutyric acid improved culture health overall. In an experiment involving 115 culture lines, 0.66 mg L-1 6-benzylaminopurine produced the highest average shoots per explant, but 0.33 mg L-1 produced the greatest proportion of shoots 2 cm or greater. Incubation for 24 h in 20 mg L-1 indole-3-butyric acid led to the most rooting. These methods show promise for the ex situ conservation of many genotypes of endangered Q. dumosa.

Harnessing the power of botanical gardens: Evaluating the costs and resources needed for exceptional plant conservation.

Premise: The effective ex situ conservation of exceptional plants, whether in living collections or cryo-collections, requires more resources than the conservation of other species. Because of their expertise with rare plants, botanical gardens are well positioned to lead this effort, but a well-developed strategy requires a clear understanding of the resources needed. Methods: Grant funding was obtained from the Institute of Museum and Library Services to support a three-year project on cryobanking, and to provide smaller grants to 10 other botanical gardens for one-year projects on either (1) seed behavior studies or (2) the development of protocols for in vitro propagation or cryopreservation. Results: Nine of the partner gardens worked on 19 species (one was unable to continue due to the COVID-19 pandemic), while the larger project focused on 14 species. A point system was developed for tasks accomplished, and the average costs per point of the larger and smaller projects were similar. Labor accounted for half the costs. Projects focused on species in the Asteraceae and Orchidaceae had lower costs per point than other species. Discussion: Both large and small projects can contribute to a strategy for exceptional plant conservation for similar costs. Prioritizing species with lower costs could help advance the field while allowing time for work on more difficult species to develop.